Exechonella verrucosa ( Canu & Bassler, 1927 ) Cáceres-Chamizo & Sanner & Tilbrook & Ostrovsky, 2017

Cáceres-Chamizo, Julia P., Sanner, Joann, Tilbrook, Kevin J. & Ostrovsky, Andrew N., 2017, Revision of the Recent species of Exechonella Canu & Bassler in Duvergier, 1924 and Actisecos Canu & Bassler, 1927 (Bryozoa, Cheilostomata): systematics, biogeography and evolutionary trends in skeletal morphology, Zootaxa 4305 (1), pp. 1-79 : 56-58

Exechonella verrucosa ( Canu & Bassler, 1927) n. comb.

( Fig. 23 , Table 22)

Coleopora verrucosa: Canu & Bassler 1927 , p. 6, 42, pl. 1, fig. 7; 1929, p. 267–268, pl. 20, fig. 4, pl. 26, fig. 9. Not Teuchopora verrucosa: Harmer 1957 , p. 898, pl. 54, figs 11–12.

Not Coleopora verrucosa: Winston & Heimberg 1986 , p. 15–16, figs 33–34.

Material examined. Holotype: USNM 8465 , encrusting on erect cheilostome fragment. Philippines, Jolo Island , Jolo Light, 6o 4´25´´N, 120o 58´30´´E, Albatross Station D. 5137, depth 20 fathoms, 5 March 1908 . Other material examined: USNM 545930 . Philippines, Jolo Island , Jolo Light, 6o 4´2´´N, 120o 58´3´´E, Albatross Station D. 5137, depth 20 fathoms, 5 March 1908 .

Description. Colony encrusting, unilaminar, multiserial. Autozooids convex, pentagonal in shape, separated by deep grooves. Zooidal periphery surrounded by a narrow gymnocystal rim in some zooids. Primary orifice subcircular, slightly wider than long, poster (one-third) slightly wider than the anter (two-thirds). Anter wall underlain by an inner lamina, which ends in small triangular condyles pointed to the orifice midline. Orifice with proximal shelf (a distalmost part of the zooidal frontal shield proximally surrounded by a wall of the peristome) that has a smooth area in its central part with its left and right areas wrinkled. Peristome short, tubular, thick-walled with pustulose external surface. Peristomes of a smaller colony show bases of 5–6 long tubular processes two of which are preserved. Frontal shield slightly pustulose being perforated by 36–50 small, circular to subcircular foramina with a gymnocystal rim raised slightly above the frontal shield and sloping towards very small central opening. In a smaller specimen the gymnocystal rim is very narrow. In a larger specimen fusions between the rims of 2–3 foramina are common. In addition, frontal shield of most autozooids bears 4–6 thick-walled hollow processes (long, spire-like, sometimes with two peaks in the better preserved specimen) which formation involves the fusion of the gymnocystal rims of 2–5 foramina, whose openings are distinguished near the process base. Processes randomly distributed across the frontal shield with some having lateral position. Numerous oval marginal pores of various sizes well seen around zooidal periphery. Vertical zooidal walls narrow and represented by multiporous mural septula with one row of communication pores. Avicularia are present on the outer raised rim of the two largest lateralmost (sometimes proximal) foramina, which external border produces a long tubular projection. In some cases gymnocystal rim of this foramen fuses with rim of 2–3 neighbour foramina. Each avicularium has a central nipple-like structure with a central pore. A thin oval mandible closes the lumen of the foramen. In some zooids luminae are slit-like or seem occluded. Oval adventitious kenozooids are recognized by 3–6 small pores. These are often associated with avicularia. Ancestrula is unknown.

Remarks. Canu and Bassler (1927, p. 6) introduced genus Coleopora with the type species C. verrucosa Canu & Bassler, 1927 mentioning hyperstomial ovicell in its description. Globular ovicell has been mentioned in this species in their next work too ( Canu & Bassler 1929, p. 267) although it was not figured in both papers. Restudy of the type specimens showed that they belong to Exechonella , thus genus Coleopora requires a new type species. It differs from Exechonella by the pseudoporous structure of its lepralioid frontal shield and requires a revision.

Philippines Thus, Exechonella verrucosa ( Canu & Bassler, 1927) should be considered as a new combination. This species is characterized by its frontal shield with numerous small foramina with small lumen, and spire-like, thick-walled hollow processes on the frontal wall and peristome. Pointed process also develops on the lateral foramen.

Harmer (1957) removed Coleopora verrucosa Canu and Bassler, 1927 to the genus Teuchopora during his study of the several specimens from the Indo–Pacific kept at the Natural History Museum, London. Later on, those from New Guinea, Philippines and Singapore (together with colonies from the Solomon Islands) were attributed to the new species E. loslosensis by Tilbrook (2006). This species also has spike-like projections on the peristome rim. Further similarities with E. verrucosa are the well-defined zooidal boundaries with chains of numerous, small and evenly spaced marginal pores, appearance of the frontal foramina and spire-like processes, and presence of one or two larger lateralmost foramina with avicularia inside (which nipple-like structures are visible on the Plate 20, A from Tilbrook 2006). The main differences between these two species are the shape of the orifice, number of frontal foramina, (about 40 in E. verrucosa and between 60–90 in E. loslosensis ) and zooidal size reaching 1.4–1.7 mm in the latter species and less than 1 mm in the former.

Winston and Heimberg (1986) described and illustrated a species of Exechonella (as Coleopora verrucosa ) with long conical processes on the frontal shield from Komodo Island, Indonesia (see also below). The authors placed it in Exechonellidae , however, due to the frontal wall and orifice characters and not in Teuchoporidae as did Harmer (1957). The major differences between this specimen from Indonesia and the studied specimens of E. verrucosa are: (1) the shape of the foramina that are slit-like in the former and round or oval in the latter, and (2) the shape of the peristome that is slightly flared with a proximal projection on its rim in the species from Komodo, and tubular with several projections in E. verrucosa .

Distribution. Exechonella verrucosa was found near Jolo Island, Philippines.

Figures

FIGURE 23. Exechonella verrucosa (Canu & Bassler, 1927) n. comb. Philippines (A, B, G: holotype USNM 8465; C ‒ F, H, USNM 545930, non-cleaned colony). A, general colony view from above. Kenozooid is shown by arrow in A. B, E, close-up of autozooid. Lateralmost foramina with avicularia shown by arrows in B. C, three non-cleaned peripheral autozooids with their orificies closed by opercula. D, details of primary orifice and peristome. Condyle shown by arrow. F, close-up of partial frontal shield showing fused foraminal rims and their broken hollow processes. G, close-up of autozooidal frontal shield showing lateralmost foramina with avicularium, foramina, frontal processes and marginal pores. H, lateralmost foramina with avicularium. Mandible edge shown by arrowhead. Scale bars: A, C = 500 µm; B, E = 200 µm; D, F, G = 100 µm; H = 50 µm.